1. Field of the Invention
The present invention relates to a display device, and more particularly to a touch panel display device and method of fabricating a touch panel display device.
2. Description of the Related Art
A touch panel device is commonly used for inputting a corresponding order by applying pressure to a position using a finger or a tool, such as a stylus. For example, the touch panel device is commonly used in automated teller machines (ATMs), and in portable information devices, such as personal display apparatus (PDA), notebook computers, and desktop personal computers. In general, liquid crystal displays (LCDs) are commonly used as the image display device to which the touch panel is mounted.
FIG. 1 is a cross sectional view of a touch panel display device according to the related art. In FIG. 1, a touch panel display device according to the related art includes a touch panel 16 bonded to a liquid crystal display panel 10. Positioned between a lower glass substrate 20A and an upper glass substrate 20B of the liquid crystal display panel 10 are interposed liquid crystal material 21 and a ball spacer 22. A lower plate of the liquid crystal display panel 10 includes a gate line 23, an insulation film 24, a pixel electrode 25A, and an alignment film 26A, which are deposited on an entire surface of the lower glass substrate 20A. In addition, the lower plate of the liquid crystal display panel 10 includes a polarized sheet 14A bonded to a rear surface of the lower glass substrate 20A by an adhesive 37C.
An upper plate of the liquid crystal display panel 10 includes a black matrix 27, a color filter 28, a common electrode 25B, and an alignment film 26B deposited on a rear surface of the upper glass substrate 20B that faces the lower glass substrate 20A. In addition, the upper plate of the liquid crystal display panel 10 includes a polarized sheet 14B that is bonded to an entire surface of the upper glass substrate 20B by an adhesive 37B. A backlight unit 12 (in FIG. 4) is positioned facing the lower plate of the liquid crystal display panel 10. The backlight unit 12 provides irradiated light to the liquid crystal display panel 10.
The touch panel 16 includes a lower transparent sheet 33 bonded to the upper polarized sheet 14B of the liquid crystal display panel 10, a lower transparent film 36A formed on the lower transparent sheet 33, an upper transparent film 36B formed on an upper transparent sheet 34, and a spacer 35 formed between the lower transparent film 36A and the upper transparent film 36B. The spacer 35 uniformly maintains a gap between the upper plate and the lower plate of the touch panel 16. The upper and the lower transparent films 36A and 36B are formed of a material, such as indium-tin-oxide (ITO), indium-zinc-oxide (IZO), and indium-tin-zinc-oxide (ITZO).
FIG. 2 is a plan view of an electrode structure of FIG. 1 according to the related art, and FIG. 3 is a perspective view of an electrode structure of the touch panel display device of FIG. 1 according to the related art. In FIGS. 2 and 3, along left and right side edges of the upper transparent film 36B are formed Y-axis electrodes 40A and 40B. The Y-axis electrodes 40A and 40B are formed by printing silver Ag on the upper transparent film 36B, and are electrically connected to tail lines 41A and 41B having a pad area in a middle portion of the right side edge to transmit power from the tail lines 41A and 41B. Along top and bottom side edges of the lower transparent film 36A are formed X-axis electrodes 42A and 42B. The X-axis electrodes 42A and 42B are formed by printing silver Ag on the lower transparent film 36A, and are electrically connected to tail lines 43A and 43B having a pad area in a middle portion of the right side edge to transmit power from the tail lines 43A and 43B. Accordingly, if a voltage is applied to the Y-axis electrodes 40A and 40B, an electric field Ex along an X-axis direction is applied between the Y-axis electrodes 40A and 40B. Similarly, if a voltage is applied to the X-axis electrodes 42A and 42B, an electric field Ey along a Y-axis direction is applied between the X-axis electrodes 42A and 42B. If the upper transparent sheet 34 is pressed by a stylus pen or a finger at a specific region, the upper transparent film 36A and the lower transparent film 36B are electrically shorted together at the specific region. Thus, since a resistance value between the X-axis and Y-axis electrodes 42A, 42B, 40A, and 40B varies in accordance with a location of the specific region, current and voltage levels change.
FIG. 4 is a perspective view of a touch panel display device system according to the related art. In FIG. 4, power is supplied to the touch panel 16 from a power supply (not shown) inside a system main body through the tail lines 41A, 41B, 43A, and 43B. Accordingly, if the power is supplied to the touch panel 16 and the upper transparent sheet 34 of the touch panel 16 is pressed at a specific position, coordinate signals of the corresponding position is supplied to a touch panel controller 4. Then, the touch panel controller 4 supplies the coordinate signals input from the touch panel 16 to the system main body 2. The system main body 2 supplies a driving signal and video data to the liquid crystal display panel 10, and supplies the power to the touch panel 16. In addition, the system main body 2 analyzes the coordinate signals input from the touch panel controller 4 and executes a corresponding order or an application program related thereto.
However, the transparent conductive film on the upper transparent sheet 34 that is directly contacted by the finger or stylus can be easily damaged or broken. For example, when executing an computer application program, a scroll bar 48 is displayed along a right edge of a corresponding computer application window, as shown in FIG. 5. If the scroll bar 48 is moved along a Y-axis direction while pressing the upper transparent sheet 34 on the touch panel 16 with a finger or stylus, the upper transparent film 36B may be damaged or broken during operation. If the upper transparent film 36B is broken, reliability of operation that a screen is scrolling upward and downward on the scroll bar 48 is compromised. In addition, if the upper transparent film 36B is broken, the touch panel 16 will not function properly. Specifically, the edge of the touch panel 16 where the scroll bar 48 is located is considered a dead space margin (DSM) area where a height difference is generated between the Y-axis electrodes 40a and 40b and the upper transparent film 36B. Accordingly, the upper transparent film 36B is more likely to be broken.